Aluminum matrix texture and particle characterization in Al-Al3Ti FGMs produced by a centrifugal solid-particle method

The centrifugal solid-particle method has proved to be effective in producing functionally graded materials (FGMs). In this study, Al-Al3Ti FGMs, were produced by this centrifugal method, from an Al-5 wt % Ti master alloy. Applied centrifugal forces were 30, 60 and 120G (units of gravity). Samples from the outer surface of each specimen were cut and aluminum matrix texture analyzed by Schulz reflection method. Analysis of the resulting pole figures indicates a preferred orientation along the (200) plane for the aluminum matrix crystals. Furthermore, increasing the applied centrifugal force enhances the orientation effect. Al3Ti platelet orientation and area fraction at the samples’ outer surface along three observation planes were also measured. The Al3Ti platelets in the outer region are orientated perpendicular to the centrifugal force direction along two of the observed planes, also an increase in centrifugal force leads to an increase in orientation in those two planes. The intermetallic particle volume fraction also increases with higher applied centrifugal force, although not significantly. A correlation appears to exist between particle orientation and the preferred orientation of the matrix.(undefined

Particle distribution and orientation in Al-Al3Zr and Al-Al3Ti FGMs produced by the centrifugal method

Al-Al3Zr and Al-Al3Ti functionally graded materials (FGMs) were produced by a centrifugal method from Al-5wt% Zr and Al-5wt% Ti alloys, respectively. Applied centrifugal forces were 30, 60 and 120G (units of gravity). Microstructural characterization was performed to evaluate the intermetallic particles’ distribution and orientation. Knoop hardness tests were carried out, with the indenter’s long diameter normal to the centrifugal force direction. Both the Al3Zr and the Al3Ti intermetallic particles are platelet in morphology. These platelets tend to be oriented normal to the centrifugal force direction. Higher applied centrifugal force increases both the intermetallic platelet volume fraction as well as their orientation in the outer regions of the fabricated FGM rings. Also higher orientation and volume fraction distribution are observed in the Al- Al3Ti FGMs. Knoop hardness measurements in general follow the same trend as the intermetallic particle volume fraction for each sample.(undefined

Microstructural characterization and tribocorrosion behaviour of Al/Al3Ti and Al/Al3Zr FGMs

Al/Al3Ti and Al/Al3Zr functionally graded materials (FGMs) were manufactured through a centrifugal method from Al–5 mass % Ti and Al–5 mass % Zr, respectively. Applied centrifugal forces were 30, 60 and 120 G (units of gravity). Microstructural characterization was performed and the influence of the reinforcing phase on the tribocorrosion behaviour of the FGMs was investigated. An increase in both the particles volume fraction as well as their orientation in the outer regions of the FGMs was found as the applied centrifugal force increased. Better tribocorrosion behaviour was found in the samples containing the highest concentration of reinforcing particles. However the microstructure below the surface appears to influence the tribocorrosion behaviour.The authors gratefully acknowledge the financial support provided by "Tokai Region Nanotechnology Manufacturing Cluster in KNOWLEDGE CLUSTER INITIATIVE" by the Ministry of Education, Culture, Sports, Science and Technology of Japan. Acknowledgments are also due to "FCT", Portugal, through the project SFRH/BPD/5518/2001

Electrodeposition of Zn-Mn alloys from recycling battery leach solutions in the presence of amines

The recovery of metal ions by electrodeposition from solutions resulting from the lixiviation of spent Zn-MnO2 batteries was studied. It was attempted to optimise the electrodeposition process, the selectivity of ion-separation, the morphologic characteristics, and the anticorrosive and galvanic properties of metallic deposits. The simultaneous deposition of zinc and manganese on different ferrous substrates under various experimental conditions was tested. This allowed us to access the efficiency of the electrodeposition, the morphology and composition of the metallic deposits, as well as their performance as galvanic coating layers. The effect of amine additives, namely, of methylamine and ethylenediamine, on the properties of the coatings was also studied. It was shown that the amines with buffering or passivating effects improve the simultaneous deposition of Mn

Puzzled: Navigating extractive policy information jigsaws for best practice and transparency

This viewpoint article was written in response to our attempt to explore mechanisms that promote financial 'transparency' in the minerals and energy extractive. We controversially forward our opinion that the trajectory of existing transparency mechanisms is likely to generate an obfuscating mass of disclosed information-not 'transparency'. Using a jigsaw analogy, we make a distinction between 'disclosure' and achieving the more challenging 'transparency': it is both being able to have the pieces (disclosure), and put them together to see the big picture. It is just as important to identify missing pieces of the puzzle to prevent selective disclosure. We critically analyze extractive financial policy, and provide an example where a 'best practice' mining securities policy has markedly advanced transparency in a major mining state. The policy substantially reduces government financial risk of a mining company default at no additional cost; reduces costs to industry around ten-fold; incentivises ongoing site rehabilitation; creates a fund for historical abandonments; and; sustains an impressive publically available information instrument of disturbed footprints and associated rehabilitation for every tenement at high precision on an annual basis. Yet it still remains deficient in terms of transparency in particular aspects, of which we clarify and discuss

Nuevos datos sobre la sucesión del "CXG" (Grupo das Beiras) : evidencia sedimentaria del origen glacioderivado de las facies conglomeráticas de la FM. del Cabeço das Popas, en la región de Monfortinho (Portugal Central)

La presencia de "dropstones" en las facies finas laminadas que se intercalan entre los orto y paraconglomerados característicos de la Fm. del Cabeço das opas (CXG: Grupo das Beiras), prueba su origen glacioderivado. La edad véndica media-superior considerada para esta Fm. permite postular la existencia de episodios glaciares postvarangerienses en el Macizo Hespérico